This invention relates in general to devices for use in footwear to correct and prevent foot-related problems and to correct foot abnormalities.
The anatomical bone structure in the human leg and foot is such that for many individuals foot and other problems develop from physical activities such as walking and running. Among these problems are fallen arches, ankle sprains and uneven shoe heel wear. Athletes, especially runners, develop foot-related problems such as heel spur pain or "jogger's heel," "runners's knee" and some hip and sciatic nerve conditions. In children angle of gait problems can develop, such as duck feet and pigeon-toed conditions.
In many cases the "runner's knee" syndrome is athletes can be traced directly to foot problems. The human anatomy is such that the leg bones extend inwardly from the hip joints at an angle which is generally on the order of 4.degree. to 5.degree. from vertical. This creates an outward tilt of each heel on the order of 4.degree. to 5.degree. from the floor, ground or other supporting surface. As the individual walks or runs the heel tilt condition results in an inward rolling of the heel bones about the subtalar joint below the ankle. This causes a pronating motion of the foot which is carried up through the tibia to the knee joint with resulting trauma to that joint.
A number of different orthopedic devices have heretofore been developed in attempts to correct specific foot problems. Among the relevant prior art patents is U.S. Pat. No. 2,086,242 to Sheridan which provides a foot appliance having support pads positioned to maintain alignment of the foot structure for correcting foot troubles such as fallen arches.
U.S. Pat. No. 2,255,100 to Brady provides a heel pad which is insertable into a shoe for purposes of correcting posture.
U.S. Pat. No. 3,566,486 to Conway provides a shoe having a wedge structure holding the foot in a manner to relax the calf muscles and to hold the foot in alignment with the shoe sole.
U.S. Pat. No. 2,821,032 to Helfet provides an orthopedic device for correcting deformities such as flat-footedness caused by heel eversion.
British Pat. No. 780,769 provides a device insertable into a boot or shoe to form a cup-shaped support for the heel.
Orthopedic appliances such as orthotic devices are currently used by podiatrists as specific treatment for "runner's knee." Such orthotic devices are prescribed for individual patients and are typically made by first casting a mold of heel and sole portions of the patient's foot. The mold is then used to make the orthosis with an upper surface conforming to the heel and sole contour and with a wedge placed under the heel to prevent the inward rolling. However, such orthoses do not provide stabilization and support for the heel relative to vertical, and they are relatively expensive in view of the requirement to prescribe and construct them specifically for individual patients.